Method of manufacturing folded structure with additive features

ABSTRACT

A method of manufacturing a multi-sided or otherwise relatively three-dimensional formed structure for, e.g., an aerospace vehicle. A relatively planar base structure is constructed using a first construction technique. Features (e.g., ribs) are incorporated into the base structure using a second construction technique (e.g., additive or subtractive manufacturing) to create an intermediate structure. The intermediate structure is folded along fold-lines or otherwise physically formed to create the formed structure, such that some of the features are located within an internal space defined by the formed structure. Joints between the sides of the formed structure are welded, fastened, or otherwise secured. Separately constructed additional elements (e.g., bulkheads) may be incorporated into the structure. A closeout element may be added to the formed structure to further define and close the internal space. Throughout the process, the structures, features, and elements may be refined to desired tolerances.

RELATED APPLICATIONS

The present application is a continuation application and claimspriority of co-pending U.S. patent application Ser. No. 16/929,195,filed on Jul. 15, 2020, and entitled “METHOD OF MANUFACTURING FOLDEDSTRUCTURE WITH ADDITIVE FEATURES”, which is hereby incorporated in itsentirety by reference herein.

FIELD

The present invention relates to methods of manufacturingthree-dimensional structures, and more particularly, embodiments providea method of manufacturing a multi-sided or otherwise three-dimensionalstructure as a relatively planar base structure to which is added and/orsubtracted features and which is subsequently folded or otherwisephysically formed to achieve the three-dimensional structure.

BACKGROUND

In the manufacture of aerospace and other vehicles and structures, it isoften desirable to economically manufacture integrated structures whileminimizing required secondary joining operations such as welding andfastening. One solution is to begin with a block of raw material havingdimensions equal to or greater than the finished structure, and then usesubtractive manufacturing technology to remove material from the blockuntil the desired three-dimensional structure is achieved. However thissolution is time-consuming and can be wasteful and undesirablyexpensive. Another solution is to use additive manufacturing to build-upmaterial until the desired three-dimensional structure is achieved.However, this solution is also time-consuming and can encounterlimitations creating complex internal components. A third solution is tomanufacture several individual pieces, and then use jigs and joining orfastening technologies to position and secure the pieces to achieve thethree-dimensional structure. However, this solution is alsotime-consuming and is highly skill dependent because improperpositioning of the jigs and/or employment of the joining or fasteningtechnologies can result in an inaccurate, weak, or otherwise unusablestructure.

This background discussion is intended to provide information related tothe present invention which is not necessarily prior art.

SUMMARY

Embodiments address the above-described and other problems andlimitations in the prior art by providing a method of manufacturing amulti-sided or otherwise three-dimensional structure as a relativelyplanar base structure to which is added and/or subtracted features tocreate an intermediate structure which is subsequently folded orotherwise physically formed to achieve the three-dimensional formedstructure.

In a first embodiment, a method is provided for manufacturing athree-dimensional formed structure, and the method may comprise thefollowing steps. A base structure may be constructed, and one or morefeatures may be incorporated into the base structure to create anintermediate structure. The intermediate structure may be physicallyformed to create the three-dimensional formed structure, such that atleast one of the features may be located within an internal spacedefined by the formed structure. One or more joints between two or moresides of the formed structure may be secured to complete the basicbuild.

Various implementations of the first embodiment may include any one ormore of the following features. The base structure may be constructedfrom wrought plate metal and may include one or more thicker areasassociated with one or more attachment points of the formed structure.At least one of the features may be incorporated into the base structureusing an additive manufacturing technique. The features may include oneor more stiffening ribs configured to physically stiffen the formedstructure. Forming the intermediate structure to create the formedstructure may include folding the intermediate structure. Theintermediate structure may include one or more fold lines whichfacilitate forming the formed structure by folding the intermediatestructure along the fold lines. The method may further include, prior toforming, refining to a tolerance an area of the intermediate structurewhich may be located within the internal space after forming. Some orall of the joints may be secured by welding or fastening. The method mayfurther include incorporating one or more separately constructedadditional elements into the intermediate structure prior to forming orinto the formed structure after forming. The separately constructedadditional elements may include a bulkhead extending across the internalspace. The method may include incorporating a closeout element into theformed structure, and the closeout element may further define and closethe internal space.

In a second embodiment, a method is provided for manufacturing amulti-sided formed structure. The method may comprise the followingsteps. A base structure may be constructed using a first constructiontechnique, and one or more features may be incorporated into the basestructure using a second construction technique to create anintermediate structure which may include one or more fold lines. An areaof the intermediate structure which will be located within an internalspace defined by the formed structure may be refined to a tolerance. Theintermediate structure may be folded along the fold lines to create theformed structure having two or more sides, and at least one of theadditional features may be located within the internal space defined bythe formed structure. One or more joints between the sides of the formedstructure may be secured to complete the basic build.

Various implementations of the second embodiment may include any one ormore of the following features. The base structure may be constructedfrom wrought plate metal and may comprise one or more thicker areasassociated with one or more attachment points of the formed structure.The second construction technique may be an additive manufacturingtechnique. The features may include one or more stiffening ribsconfigured to physically stiffen the formed structure. At least one ofthe joints may be secured by welding. The method may further includeincorporating one or more separately constructed additional elementsinto the intermediate structure prior to forming or into the formedstructure after forming. The method may further include incorporating acloseout element into the formed structure, and the closeout element mayfurther define and close the internal space.

This summary is not intended to identify essential features of thepresent invention, and is not intended to be used to limit the scope ofthe claims. These and other aspects of the present invention aredescribed below in greater detail.

DRAWINGS

Embodiments of the present invention are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is an isometric view of an example relatively planar basestructure;

FIG. 2 is an isometric view of example features added to the basestructure of FIG. 1 to create an example intermediate structure;

FIG. 3 is an isometric view of the intermediate structure of FIG. 2physically formed into an example multi-sided or otherwisethree-dimensional formed structure;

FIG. 4 is a fragmentary cross-sectional elevation view of an examplefeature added to the base structure during the creation of theintermediate structure of FIG. 2 ;

FIG. 5 is a fragmentary cross-sectional elevation view of theintermediate structure of FIG. 4 , wherein the feature and the basestructure have been refined by removing material;

FIG. 6 is a semi-cross-sectional isometric view of the formed structureof FIG. 3 showing separately constructed features added to the formedstructure;

FIG. 7 is a fragmentary cross-sectional elevation view of animplementation of a fold-line element of the intermediate structure ofFIG. 2 prior to forming;

FIG. 8 is a fragmentary cross-sectional elevation view of the fold-lineelement of FIG. 7 after forming;

FIG. 9 is a fragmentary cross-sectional elevation view of anotherimplementation of two fold-line elements of the intermediate structureof FIG. 2 prior to forming;

FIG. 10 is a fragmentary cross-sectional elevation view of the twofold-line elements of FIG. 9 after forming;

FIG. 11 is a cross-sectional elevation view of another implementation ofmultiple fold-line elements after forming to create a substantiallycircular or cylindrical formed structure;

FIG. 12 is a cross-sectional elevation view of the formed structure ofFIG. 3 to which has been added a closeout element; and

FIG. 13 is a flowchart of steps in an embodiment of a method ofmanufacturing a multi-sided or otherwise three-dimensional formedstructure, wherein the results of various implementations the steps arereflected in FIGS. 1-12 .

The figures are not intended to limit the present invention to thespecific embodiments they depict. The drawings are not necessarily toscale.

DETAILED DESCRIPTION

The following detailed description of embodiments of the inventionreferences the accompanying figures. The embodiments are intended todescribe aspects of the invention in sufficient detail to enable thosewith ordinary skill in the art to practice the invention. Theembodiments of the invention are illustrated by way of example and notby way of limitation. Other embodiments may be utilized and changes maybe made without departing from the scope of the claims. The followingdescription is, therefore, not limiting. The scope of the presentinvention is defined only by the appended claims, along with the fullscope of equivalents to which such claims are entitled.

In this description, references to “one embodiment,” “an embodiment,” or“embodiments” mean that the feature or features referred to are includedin at least one embodiment of the invention. Separate references to “oneembodiment,” “an embodiment,” or “embodiments” in this description donot necessarily refer to the same embodiment and are not mutuallyexclusive unless so stated. Specifically, a feature, component, action,step, etc. described in one embodiment may also be included in otherembodiments, but is not necessarily included. Thus, particularimplementations of the present invention can include a variety ofcombinations and/or integrations of the embodiments described herein.

Broadly characterized, embodiments provide a method of manufacturing amulti-sided or otherwise three-dimensional structure as a relativelyplanar base structure to which is added and/or subtracted features andwhich is subsequently folded or otherwise physically formed to achievethe three-dimensional structure. More specifically, a multi-sidedstructure may be created “in-the-flat” using homogeneous and/or hybridmaterial manufacturing techniques and then subsequently folded orotherwise physically formed to a final shape. Embodiments advantageouslyreduce the cost, time, and complexity of manufacturing multi-sided orotherwise three-dimensional structures, including facilitating theincorporation of complex internal features and minimizing requiredsecondary joining operations such as welding and fastening. Potentialapplications include manufacturing higher performance damage tolerantintegrated metallic structures, such as may be used in aerospace orother vehicles or structures.

In various example implementations shown in FIGS. 1-12 , an initial basestructure may be constructed, as seen in FIG. 1 ; one or more features32 may be added to, subtracted from, or otherwise incorporated into thebase structure 30 to create an intermediate structure 34, as seen inFIG. 2 ; the intermediate structure 34 may be folded or otherwisephysically formed into a multi-sided or otherwise three-dimensionalformed structure 36, as seen in FIG. 3 , wherein at least one or more ofthe features 32 may be located within an internal space 38 defined bythe formed structure 36, and joints or other connections (e.g., betweenthe sides of the formed structure 36) may be welded, fastened, orotherwise secured. If a closeout element 40, as seen in FIG. 12 , isdesired or needed, it may be added. At any one or more points in thisprocess, the structures, features, and/or elements may be refined todesired tolerances, especially areas which may be located in theinternal space 38 within the formed structure 36 and therefore difficultto access after forming.

In one example implementation, the formed structure 36 may be anaerospace or other vehicle structure, such as an engine pylon. The basestructure 30 may be “relatively planar” in comparison to the “relativelythree-dimensional” formed structure 36 in that the forming process mayincrease or add to the dimensionality of the original base structure 30.The base structure 30 may be constructed using a first constructiontechnique, such as physical shaping (the base structure 30 may be, e.g.,wrought plate metal), additive manufacturing, or subtractivemanufacturing, and at least some of the features 32 may be constructedusing a second construction technique which may or may not be differentfrom the first construction technique, such as an additive manufacturingtechnique in which at least some of the features 32 are deposited ontothe base structure 30. This advantageously reduces the needed amount ofraw material, as compared to, for example, machining the intermediate orformed structure with the features from a thick plate or forging.

Construction of the base structure 30 may include locating criticallyloaded interface features 44 within the base material volume. Forexample, in a pylon these interfaces may include the major wing attachfitting lugs. The width of these lugs may determine the minimumthickness of the base material. If a load bearing requirement is drivingthe lug thickness, the required thickness of the base material may befurther reduced by adding material to one or both sides of the basematerial using an additive manufacturing technique to provide therequired bearing surface area.

As seen in FIGS. 4 and 5 , at least some of the features 32, such asstiffening ribs, which exceed the base material volume may be built-up(FIG. 4 ) using an additive manufacturing technique, and thensubsequently refined (FIG. 5 ) to a desired shape or design. One suchtechnique may involve fusion deposition using plasma melt wire. Bulkadditive manufacturing techniques may include linear or rotary frictionwelding, and the bulk materials may include similar, gradated, or hybridprefabricated forms. Pylon-to-wing attach features are typically thickerthan other structural elements. This results in the final machinedprofile being located within the base material rather than at the addedmaterial interface with the base material. As the base of stiffeningribs tend to be higher shearing stress locations, it is advantageous forthis feature to be located away from the fusion plane of the addedmaterial and the base material. Additionally or alternatively, negativefeatures, such as grooves, openings, or thinner areas, may be createdusing a subtractive manufacturing technique.

As seen in FIGS. 1, 2, and 7-11 , one or more integral features 46 whichfacilitate folding or other forming of the structure may be incorporatedinto the base structure 30 or added thereto and/or subtracted therefrom.For example, folding may be facilitated by reducing the cross-sectionalthickness of the base structure 30 along one or more fold-lines 46.Folding or other forming may be further facilitated by heating (using,e.g., Joule-forming) the fold-lines 46 or other areas of theintermediate structure 34 prior to folding or other manipulation.Features 48 may be incorporated into one or both sides of fold-line 46to strengthen the interior joint 50 once the structure 36 is formed.This joint 50 may be consolidated into an integrated structure by fusionwelding techniques, such as plasma or electron beam welding. Formaterials that allow solid-state joining techniques, friction stirwelding may be used. A mandrel may be used to aid in forming the jointgeometry. This may be a removable tool, a “dissolvable” tool, or a“fly-away” tool. In the case of removable or dissolvable tools, they mayfacilitate fusion joining of the interior joint by acting as abeam-stopper or splatter shield such as is used in electron beamwelding. The fly-away tool may be a metal matrix composite componentthat is fused or brazed to the structure during forming or post-forming.

Once the structure 36 is folded or otherwise formed, internal features32 and/or elements may be secured by, e.g., welding or fastening. Someof these may be features 32 which were added to the base structure 30and which take their final positions once the structure 36 is formed,while, as seen in FIG. 6 , others of these elements 52 may be separatelyfabricated elements, such as bulkheads or ribs, which are introducedduring or after forming. As desired or needed, the closeout element 40may be installed and secured to the formed structure 36 to complete thebasic build. At any one or more points in this process, the structures,features, and/or elements may be refined to desired tolerances,especially areas which may be located in the internal space 38 withinthe formed structure 36 and therefore difficult to access after forming.

Although the main structure configuration has been described and shownusing simple plate geometric representations, this geometry could be apartially or fully machined truss or a complete additive manufacturedcomponent. Additionally, the internal features may be configured in sucha way that they interface with cooperating features, when folded, in athree-dimensional manner. Additionally, features which facilitate attachor mounting of other components may be incorporated prior to forming.One such feature may be threaded studs installed using a fusion process,such as robotic rotary friction welding. Additionally, while depicted asa two-piece structural assembly, the method may be used to fabricatemultiple pieces joined along two or more edges or other locations toform a structure of open or closed shape.

Referring also to FIG. 13 , an embodiment of a method 130 is shown formanufacturing a multi-sided or otherwise three-dimensional formedstructure, such as was described above, as a relatively planar basestructure to which is added and/or subtracted features and elements andwhich is subsequently folded or otherwise physically formed to achievethe formed structure. With reference to FIGS. 1-12 and the precedingdiscussion, the method 130 may include the following steps.

An initial base structure 30 may be constructed, as shown in 132 andFIG. 1 . The base structure 30 may be constructed using substantiallyany suitable base material or materials and substantially any suitablefirst construction technique, such as physical shaping (the basestructure 30 may be, e.g., wrought plate metal), additive manufacturing,or subtractive manufacturing. The base structure 30 may be relativelyplanar in comparison to the formed structure 36 in that the formingprocess may increase or add to the dimensionality of the original basestructure 30 (as reflected in FIGS. 1-3 ). In one implementation, thebase structure 30 may be constructed of wrought metal. The basestructure 30 may be relatively planar or non-planar, may include thickeror otherwise reinforced areas, and may include one or more initiallyincorporated features 46 (e.g., fold lines or ribs). The base structure30 and any initially incorporated features 46 may be refined, as shownin 134 and seen in FIG. 1 , using substantially any suitableconstruction technique.

One or more features 32 may be incorporated into the base structure 30to create an intermediate structure 34, as shown in 136 and seen in FIG.2 . The features 32 may be constructed from substantially any suitablefeature material or materials and using substantially any suitablesecond construction technique which may or may not be different from thefirst construction technique. For example, as seen in FIGS. 4 and 5 , atleast some of the features 32 may be constructed using an additivemanufacturing technique in which at least some of the features 32 aredeposited onto the base structure 30. The features 32 may include, e.g.,structural or non-structural elements, fold lines, ribs, bulkheads,attachments, or openings or closings. For example, base material may beremoved in order to form or refine fold lines 46, or material may beadded to the base structure 30 to build-up ribs or other features. Atleast one or more of the features 32 may be located within an internalspace 38 defined by the formed structure 36. The intermediate structure34 may be refined, as shown in 138, using substantially any suitablerefinement technique. The two prior steps of construction and refinementmay be repeated as needed or desired. For example, complex features 32on the intermediate structure 34 may be constructed through severalstages of building and refining.

The intermediate structure 34 may be physically formed to create aformed structure 36, as shown in 140 and seen in FIG. 3 . Forming mayinvolve substantially any suitable action or actions, such as folding,rolling, bending, compressing, or stretching, which may be performed atany suitable temperature (e.g., a higher temperature to soften materialand facilitate shaping). For example, as shown in the figures, arelatively planar intermediate structure 34 may be folded to create amulti-sided or otherwise relatively three-dimensional formed structure36, as seen in FIGS. 8, 10, and 11 . Joints 50 and other interfaces andconnections may be secured, as shown in 142. Securement may involvesubstantially any suitable technique, such as welding, fastening, orbonding. The formed structure 36 may be refined, as shown in 144, usingsubstantially any suitable refinement technique.

Any additional internal or external features may be incorporated intothe formed structure 36, as shown in 146 and seen in FIG. 6 , which maycomplete the basic build. Additional internal features may include,e.g., bulkheads or frame members, and additional external features mayinclude, e.g., a closeout element 40 (FIG. 12 ). In someimplementations, the formed structure 36 may include an opening allowingaccess to the interior of the structure, and the closeout element 40 mayspan this opening to further define or close the internal space 38 orotherwise complete the basic structure. The formed structure 36 may befurther refined and/or constructed, as shown in 148, using substantiallyany suitable refinement technique. This may include, for example,machining critical features to ensure a needed or desired degree ofaccuracy of tolerance.

Although the invention has been described with reference to the one ormore embodiments illustrated in the figures, it is understood thatequivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims.

Having thus described one or more embodiments of the invention, what isclaimed as new and desired to be protected by Letters Patent includesthe following:
 1. A method of manufacturing a three-dimensional formedengine pylon structure, the method comprising: constructing a basestructure; creating one or more fold lines of reduced cross-sectionalthickness in the base structure; incorporating one or more features intothe base structure to create an intermediate structure; physicallyforming the intermediate structure, including folding the intermediatestructure along the one or more fold lines of reduced cross-sectionalthickness, to create the three-dimensional formed engine pylonstructure, wherein at least one of the one or more features is locatedwithin an internal space defined by the three-dimensional formed enginepylon structure; and securing one or more joints between two or moresides of the three-dimensional formed engine pylon structure.
 2. Themethod of claim 1, wherein the base structure is constructed fromwrought plate metal and comprises one or more thicker areas associatedwith one or more attachment points of the three-dimensional formedengine pylon structure.
 3. The method of claim 1, wherein at least oneof the one or more features are incorporated into the base structureusing an additive manufacturing technique.
 4. The method of claim 1,wherein the one or more features include one or more stiffening ribsconfigured to physically stiffen the three-dimensional formed enginepylon structure.
 5. The method of claim 1, further including, prior toforming, refining to a tolerance an area of the intermediate structurewhich will be located within the internal space after forming.
 6. Themethod of claim 1, further comprising two protrusions extending from theintermediate structure within the internal space, located to oppositesides of one of one of the one or more fold lines of reducedcross-sectional thickness.
 7. The method of claim 6, wherein the twoprotrusions are positioned such that the two protrusions abut each otheronce either or both of the two protrusions are pivoted in a directiontoward each other about the one of the one or more fold lines of reducedcross-sectional thickness.
 8. The method of claim 1, wherein at leastone of the one or more joints are secured by welding.
 9. The method ofclaim 1, wherein at least one of the one or more joints are secured byfastening.
 10. The method of claim 1, further including incorporatingone or more separately constructed additional elements into theintermediate structure prior to forming or into the three-dimensionalformed engine pylon structure after forming.
 11. The method of claim 10,wherein the one or more separately constructed additional elementsinclude a bulkhead extending across the internal space.
 12. The methodof claim 1, further including incorporating a closeout element into thethree-dimensional formed engine pylon structure, wherein the closeoutelement further defines and closes the internal space.
 13. A method ofmanufacturing a multi-sided formed engine pylon structure, the methodcomprising: constructing a base structure using a first constructiontechnique; creating one or more fold lines of reduced cross-sectionalthickness in the base structure; incorporating one or more additionalfeatures into the base structure using a second construction techniqueto create an intermediate structure; refining to a tolerance an area ofthe intermediate structure which will be located within an internalspace defined by the multi-sided formed engine pylon structure; foldingthe intermediate structure along the one or more fold lines of reducedcross-sectional thickness to create the multi-sided formed engine pylonstructure having two or more sides, wherein at least one of the one ormore additional features is located within the internal space defined bythe multi-sided formed engine pylon structure, wherein two protrusionsextending from different ones of the two or more sides within theinternal space are positioned proximate one of the one or morefold-lines of reduced cross-sectional thickness such that the twoprotrusions abut each other following completion of the folding step,thereby strengthening the multi-sided formed structure; and securing oneor more joints between the two or more sides of the multi-sided formedstructure.
 14. The method of claim 13, wherein the base structure isconstructed from wrought plate metal and comprises one or more thickerareas associated with one or more attachment points of the multi-sidedformed engine pylon structure.
 15. The method of claim 13, wherein thesecond construction technique is an additive manufacturing technique.16. The method of claim 13, wherein the one or more features include oneor more stiffening ribs configured to physically stiffen the multi-sidedformed engine pylon structure.
 17. The method of claim 13, wherein atleast one of the one or more joints are secured by welding.
 18. Themethod of claim 13, further including incorporating one or moreseparately constructed additional elements into the intermediatestructure prior to forming or into the multi-sided formed engine pylonstructure after forming.
 19. The method of claim 13, further includingincorporating a closeout element into the multi-sided formed enginepylon structure, wherein the closeout element further defines and closesthe internal space.
 20. A method of manufacturing a multi-sided formedengine pylon structure which is a component of an aerospace vehicle, themethod comprising: constructing a base structure using a firstconstruction technique; creating one or more fold lines of reducedcross-sectional thickness in the base structure; incorporating one ormore additional features into the base structure using an additivemanufacturing technique to create an intermediate structure, wherein theone or more additional features include one or more stiffening ribsconfigured to physically stiffen the multi-sided formed engine pylonstructure; refining to a tolerance an area of the intermediate structurewhich will be located within an internal space defined by themulti-sided formed engine pylon structure; folding the intermediatestructure along the one or more fold lines of reduced cross-sectionalthickness to create the multi-sided formed engine pylon structure havingtwo or more sides, wherein at least one of the one or more additionalfeatures is located within the internal space defined by the multi-sidedformed engine pylon structure, wherein two protrusions extending fromdifferent ones of the two or more sides within the internal space arepositioned proximate one of the one or more fold-lines of reducedcross-sectional thickness such that the two protrusions abut each otherfollowing completion of the folding step, thereby strengthening themulti-sided formed structure; welding one or more joints between the twoor more sides of the multi-sided formed structure; and incorporating acloseout element into the multi-sided formed structure, wherein thecloseout element further defines and closes the internal space.